Method of cleaning metal articles.



J. D. PHILLIPS 812.0. HAMBUEGHEN.

METHOD OF CLEANING METAL ARTIGLES.

APPLICATION FILED AUG. 6, 1909.

Patented Jan. 11, 1910.

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JAMES D. PHILLIPS AND CARL HAMBUECHEN, 0F MADISON, WISCONSIN.

METHOD OF CLEANING METAL ARTICLES.

Specification of Letters Patent.

Patented Jan. 11, 1910.

Application filed August 6, 1909. Serial No. 511,540.

To all whom it may concern:

Be it known that we, JAMES D. PHILLIPS and CARL HAMBUECHEN, citizens of the United States, residing at Madison, in the county of Dane and State of Wisconsin, have invented certain new and useful Improvements in Methods of Cleaning Metal Articles, of which the following is a specification.

This invention relates to the cleaning of tarnished metallic surfaces, the object of the invention being the provision of a method whereby silver, gold and other metallic articles may be quickly and effectively cleaned preparatory to polishing.

" It has been heretofore proposed (British patent N o. 7027 of 1905 to Ransfordito clean silver articles by immersing them in a hot alkaline solution in a tin-lined vessel, whereby the silver becomes the cathode of a voltaic couple, and the coating or tarnish is electrolytically reduced and rendered easy of removal. It has also been proposed to use instead of tin-lined vessels, dishes of aluminum, or metallic plates or baskets as anodes. It is found in practice that such metallic anodes become coated after. a short period of use with a film or coating which is difficult to remove, and which prevents effective electrical contact between the article to be cleaned and the electropositive metal, as tin or aluminum. According'to the present invention the efiiciency of the cleaningoperation is maintained by the provision of means whereby effective electrical connection is at all times secured between the electropositive metal, as zinc, aluminum or tin, hereafter referred to as the cleaning metal, and the silver or other article to be cleaned. \Ve have found as the result of numerous experiments that the coating or film formed upon the cleaning metal is porous in character and does not seriously interfere with the electrolytic action, provided efi'ective electrical connection is secured between the cleaning metal and the metal to be cleaned:

reference is made to the accompanying drawing illustrating certain applications of our method.

In said drawing: Figure 1 is a vertical central section illustrating the principle of the invention; Fig. 2 is a similar View on line 2-2 of Fig. 3; Fig. 3 is a plan view of the apparatus shown in Fig. 2; and Figs. l, 5, are vertical sectional views of modified types of apparatus.

If an electropositive metal, as for example zinc, be maintained in effective electrical contact with a metal or alloy electronegative thereto, as for example, tin, silver, solder, ctc., the latter metal or alloy will remain bright, and may be used to secure an effective electrical contact with the article to be cleaned. This metal or alloy through which the contact is made between the metal to be cleaned and the cleaning metal will be termed for convenience the auxiliary metal. The auxiliary metal may be the same as the metal to be cleaned, or electropositive' or electronegative thereto, it being essential merely that it be electronegative to the cleaning metal. Preferably, however, the auxiliary metal is intermediate in solution tension between the cleaning metal and the metal to be cleaned.

Referring to Fig 1, 1 represents a vessel which may-be of enameled ware; 2 is the article to be cleaned, for example a silver dish; 3 is the cleaning metal, consisting in this case of a zinc rod having a terminal 4; 5 is the auxiliary metal which may be of tin, lead, silver, etc.; and 6 is a. wire establishing contact between the cleaning and auxiliary'metals. If now an alkaline solution, as for example a solution prepared by dissolving one tablespoonful of baking soda and one-half tablespoonful of common salt in one quart of water, be poured into the vessel 1, an electrolytic action will be set up by which the cleaning metal 3 will tend to pass into solution, theauxiliary metal 5 being kept bright and therefore making effective electrical contact with the article 2, which will be quickly cleaned. The cleaning metal 3 will become coated with the porous film, as above described, but the arrangement is such that this film in no way impairs the electrical contact with the article to be cleaned, and it is found in practice that the operation ma be continued for long periods without su stantial loss of efliciency. The solution is preferably but not necessarily heated.

In the above example the contact between the cleaning and auxiliar metals is made outside the solution, and'is of a temporary "of the vessel 1.

character, but this is not essential. The disosition of parts may be varied almost inefinitely, and in the drawing it has been attempted only to show by way of example a few effective embodiments of the principle above illustrated.

In Figs. 2 and 3, 1 represents a vessel which may be of tin, enameled ware, or other material, and 3 a corrugated or ribbed disk or sheet of an electropositive metal, as zinc or aluminum, lying loosely in the bottom The upper portions of the ridges or corrugations are tinned or soldered as indicated at 5 this tin or solder constituting the auxiliary metal, and remaining bright and in condition to make effective electrical contact with tarnished metal articles placed in the vessel 1.. If desired the lower portions of the corrugations may also be tinned or soldered as shown, thereby not only making the plate reversible, but in case in which 1 is a vessel which may be of tin,

ranite ware, etc.', and 3" a zinc vessel fitting oosely therein and'havin a corrugated bottom, which may if desire .be separable from the vessel to facilitate cleaning. The ridges projecting into the vessel 3 are soldered as indicated at 5 providing a bri ht contact with silver or other articles to cleaned; solder may also be applied to the lower facesof the ridges but this is notessential. The corrugated bottom is preferably perforated as indicated at 6 to permit the solu-' tion to drain away when it is lifted.

Another apparatus of large effective area is shown in F1 5 in which 3 is a zinc vessel in which a asket 5 of tinned or nickel plated wire is supported, the vessel and basket being in good electrical contact. As shown, such contact is secured by attaching to a tin strip or band 9 encircling the basket, several vertically dis osed tin projections 8, the lower edges 0 which rest upon curved or projecting surfaces at its points.

or parts of contact with the article to be cleaned, this resulting in a diminished area of contact, and, it is found, an improved 1 efficiency of contact, the points, lines or surfaces of contact being kept bright and clean by friction. The results above described are also attainable, although less perfectly, by

the use of mixed metals or. alloys, as for example an alloy of zinc with about 5% of tin; other alloys of zinc and tin, or alloys of aluminum with zinc and of zinc with lead have also been used. The electronegative metal seems in such cases to act as an auxiliary metal to facilitate the cleansing operation and to maintain the efiiciency of the cleaning metal.

We claim 1. The method of cleaning tarnished metal articles, which consists in immersing 1 the same in a suitable electrolyte in COIIjHIIC'.

tion with a cleaning metal electropositive thereto, and providing electrical contact between the articles to be cleaned and the cleaning metal through an auxiliary metal electronegative to said cleaning metal.

2. The method of cleaning tarnished metal articles, which consists in immersing the same in an alkaline electrolyte in conjunction with a cleaning metal electropositive thereto, and providing electrical contact between the articles to be cleanedand the cleaning metal through an auxiliary metal electronegative to said cleaning metal.

3. The method of cleaning tarnished metal articles, which consists in immersin the same in a solution containing an alkali metal carbonate and chlorid in conjunction with a cleaning metal electropositive thereto, and providing electrical contact between the articles to be cleaned and the cleaning metal through an auxiliary metal electronegative to said cleaning metal.

4. The method. of cleaning tarnished metal articles, which consists in immersing the same in an alkaline electrolyte in conjunction with zinc, and lprovidin electrical contact between the artic es to be c eaned and the zinc through an auxiliary metal electronegative to zinc.

5. The method of cleaning tarnished metal articles, which consists in immersing the same in a suitable electrolyte in conjunction with zinc, and Providing electrical contact between the articles to be cleaned and 10 ing metal through an auxiliary metal interthe zinc through anauxiliary'metal electromediate in solution tension between the negative to zinc but electropositive to the cleaning metal and the metal to be cleaned.

metal to be cleaned. In testimony whereof, we affix our signa- 6. The method of cleaning tarnished tures in presence of two witnesses.

metal articles, which consists in immersing J LXMES PHILLIPS the same in a suitable electrolyte in conjunc- F tion with a cleaning metal electropositivel CARL HAMBUECHEN thereto, and providing electrical contact be- I lVitnesses:

tween the articles to be cleaned and the clean- I A. D. STANCLIFF, ALICE B. CRONIN. 

